New to NXT

[jpitz31]

Hello everyone,

New owner of NXT,

Have been playing around getting use to the NXT and building the canned projects. I would now like to start designing some of my own projects.

I saw in the FAQ that many users use LDD to layout projects and use Brinklink for resources for parts.

Is this the right track for learning what resources are available to build custom projects? Is there other ways to learn what parts are available and can be used for custom work?

Also I have played around with leJos NXJ but I would rather write code that is closer to C/C++, I run OS X and have read the web site http://www.teamhassenplug.org/NXT/NXTSoftware.html

about NXC, but I am concerned that NXC does not support events. Is there any robust C/C++ development platforms for NXT? I read a few posts about NXTGCC. Do most folks run code on the NXT or do they use off brick controllers for their projects?

Also is no support for events a big issue when writing for NXT?

Thanks

Joe

[mattallen37]

First of all, almost any lego part is compatible with the NXT, in some way. The parts you will need depends on what you want to be able to build. For a nice assortment of parts, check out the NXT resource kit from Lego Education. I actually haven't ever bought an "expansion" kit for my NXTs, because I already had about 20 technic sets before getting my first NXT. Technic sets are a good option for more than just extra parts. Whenever I get a technic set, I always build both models before using the parts for my own creations. Doing so has helped me a lot with learning different tips and methods, and how to design on my own.

I almost never use CAD when building. If I use CAD at all, it's after I build something, and want to have record of it.

Bricklink is great if you need specific parts, but eBay can also be great (especially for bulk lots).

As far as the SW for the NXT, I mostly just use NXC. It's true that it is limited in a lot of ways, but there are work-arounds for many things.

[jpitz31]

Thanks mattallen37 for the quick follow up. Good advice.

Joe

[tabbycatrobots]

I'm fairly new to NXT, although I've built Lego castle and train for years. I find Bricklink a great source
for parts, and for cross-referencing what parts are in what sets, and like mentioned above, a Technic set
is a great source for robot parts. The 8043 Motorized Excavator has many good parts and great ideas (new
to me), on using gears.
The Johnny NXT in Benedettelli's book, "Creating Cool Mindstorms NXT Robots" was great for new ideas
for me. This robot does require 2 NXTs, which brings me to my next suggestion.
If you are thinking of buying a 2nd NXT kit, I'd recommend the 9797 kit from Lego education. It has a
different assortment of parts, including a rechargeable battery, and a light sensor. I like the light sensor
better than the color sensor for line following a black line of white background. The web site is
<http://www.legoeducation.us>. There are also some good spare parts packs available here, and sometimes
clearance sales.
My robots are not entirely original but usually combinations of ideas from several robots, to do a new
task. I've found some good starting ideas at <http://www.nxtprograms.com/>. I then combine these with
building ideas from books by Laurens Valk, multi-taking and BlueTooth ideas from Benedettelli's book, and
ask some questions on this forum.

[h-g-t]

I personally get all my LEGO through ebay. There is usually a huge range available.

Most items are inexpensive if you are patient and avoid buying individual units; go for bulk sales or kits.

Don't bid near XMAS, the prices shoot waaay up! Normally you can get a complete, used NXT kit for around £100 - £120, although I have landed two at less than £100 (one at £85 inc p&p).

You can always sell the bits you don't want back on ebay.

Sometimes the older RCX kits can be bought quite cheaply as well and are a good source of bits. The RCX, tower and motors are still sought by many so you can sell these to defray costs.

[tabbycatrobots]

Regarding features in NXC or other languages for the NXT. I use NXC, and use multiple threads.
I'll have a thread monitoring a sensor. This thread, thread A, will interpret what is sensed. It will
write the interpreted value into a circular queue. A second thread, thread B, will read from the queue,
(producer - consumer model), and act on what it reads, e.g. turn left, slow down, raise the head.
Although this isn't real event - driven programming, thread A is creating events for thread B. With the circular
queue, where thread A only writes and thread B only reads, I don't need mutexes, which I find
painful to code, and not great for real time programming. Real time code - fast enough to respond to
the physical world around the robot. E.g. for my racing robots, thread A is the robot's brain and thread B
is the muscle, i.e. the controls the motors. Thread A monitors the color sensor, watching for color dots
on the floor and then interprets the dots based on lap number. It then puts an action in the circular queue
to stop, speed up, or ???. Thread B monitors the light sensor for line following, and makes minor
corrections to keep the robot on track, and reads the circular queue for major actions (events?).
Sorry - long answer to a short question. Bottom line - my opinion - a multi - threaded NXC program
works well for many projects.

[jpitz31]

Thanks tabbycatrobots for the cool info on threading and circular queues, that sounds very cool.
Thanks h-g-t for the good info on batch buying on ebay.
Thanks mattallen37 for the info on Techinc's sets and cad use.

Great advice thanks everyone.

Joe